Method for making a scissoring-type current-perpendicular-to-the-plane (cpp) magnetoresistive sensor with exchange-coupled soft side shields

ABSTRACT

A method for making a scissoring type current-perpendicular-to-the-plane magnetoresistive sensor with exchange-coupled soft side shields uses oblique angle ion milling to remove unwanted material from the side edges of the upper free layer. All of the layers making up the sensor stack are deposited as full films. The sensor stack is then ion milled to define the sensor side edges. The side regions are then refilled by deposition of an insulating layer. Next, the lower soft magnetic layers of the exchange-coupled side shields are deposited, which also coats the insulating layer up to and past the side edges of the upper free layer. The soft magnetic material adjacent the side edges of the upper free layer is removed by oblique angle ion beam milling. The material for the antiparallel-coupling (APC) layers is deposited, followed by deposition of the material for the upper soft magnetic layers of the exchange-coupled side shields.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a current-perpendicular-to-the-plane(CPP) magnetoresistive (MR) sensor that operates with the sense currentdirected perpendicularly to the planes of the layers making up thesensor stack, and more particularly to a scissoring-type CPP sensor withdual sensing or free layers.

2. Background of the Invention

One type of conventional MR sensor used as the read head in magneticrecording disk drives is a “spin-valve” sensor based on the giantmagnetoresistance (GMR) effect. A GMR spin-valve sensor has a stack oflayers that includes two ferromagnetic layers separated by a nonmagneticelectrically conductive spacer layer, which is typically copper (Cu) orsilver (Ag). One ferromagnetic layer adjacent the spacer layer has itsmagnetization direction fixed, such as by being pinned by exchangecoupling with an adjacent antiferromagnetic layer, and is referred to asthe reference layer. The other ferromagnetic layer adjacent the spacerlayer has its magnetization direction free to rotate in the presence ofan external magnetic field and is referred to as the free layer. With asense current applied to the sensor, the rotation of the free-layermagnetization relative to the reference-layer magnetization due to thepresence of an external magnetic field is detectable as a change inelectrical resistance. If the sense current is directed perpendicularlythrough the planes of the layers in the sensor stack, the sensor isreferred to as a current-perpendicular-to-the-plane (CPP) sensor.

In addition to CPP-GMR read heads, another type of CPP-MR sensor is amagnetic tunnel junction sensor, also called a tunneling MR or TMRsensor, in which the nonmagnetic spacer layer is a very thin nonmagnetictunnel barrier layer. In a CPP-TMR sensor the tunneling currentperpendicularly through the layers depends on the relative orientationof the magnetizations in the two ferromagnetic layers. In a CPP-GMR readhead the nonmagnetic spacer layer is formed of an electricallyconductive material, typically a metal such as Cu or Ag. In a CPP-TMRread head the nonmagnetic spacer layer is formed of an electricallyinsulating material, such as TiO₂, MgO, or Al₂O₃.

A type of CPP sensor has been proposed that does not have aferromagnetic reference layer with a fixed or pinned magnetizationdirection, but instead has dual ferromagnetic sensing or free layersseparated by a nonmagnetic spacer layer. In the absence of an appliedmagnetic field, the magnetization directions or vectors of the two freelayers are oriented generally orthogonal to one another with parallelmagnetization components in the sensing direction of the magnetic fieldto be detected and antiparallel components in the orthogonal direction.With a sense current applied perpendicularly to the layers in the sensorstack and in the presence of an applied magnetic field in the sensingdirection, the two magnetization vectors rotate in opposite directions,changing their angle relative to one another, which is detectable as achange in electrical resistance. Because of this type of behavior of themagnetization directions of the two free layers, this type of CPP sensorwill be referred to herein as a “scissoring-type” of CPP sensor. If aCPP-GMR scissoring-type sensor is desired the nonmagnetic spacer layeris an electrically conducting metal or metal alloy. If a CPP-TMRscissoring-type sensor is desired the spacer layer is an electricallyinsulating material. In a scissoring-type CPP-MR sensor, a “hard-bias”layer of ferromagnetic material located at the back edge of the sensor(opposite the air-bearing surface) applies an approximately fixed,transverse magnetic “bias” field to the sensor. Its purpose is to biasthe magnetization directions of the two free layers so that they areapproximately orthogonal to one another in the quiescent state, i.e., inthe absence of an applied magnetic field. Without the hard bias layer,the magnetization directions of the two free layers would tend to beoriented antiparallel to one another. This tendency to be orientedantiparallel results from strong magnetostatic interaction between thetwo free layers once they have been patterned to sensor dimensions, butmay also be the result of exchange coupling between the magnetic layersthrough the spacer layer. A scissoring-type of CPP-MR sensor isdescribed in U.S. Pat. No. 7,035,062 B2. Unlike in a conventional CPPGMR or TMR sensor, in a scissoring-type CPP-MR sensor there is no needfor an antiferromagnetic pinning layer. Accordingly, the read-gap andparasitic series electrical resistances are greatly reduced. Thisenables an enhanced down-track resolution and a strongermagnetoresistance signal.

While the hard bias field at the sensor back edge will tend to align themagnetization directions of the two free layers in a CPP-MR sensorgenerally orthogonal relative to one another, there is no preference forthe specific directions of the two free layer magnetizations in thequiescent state. Thus it is just as likely that a free layermagnetization direction may point in a direction at 45 degrees relativeto the hard bias magnetization direction as at 135 degrees. For thisreason longitudinal side biasing of the two free layers will stabilizethe magnetization directions in one of these two possible orientationsin the quiescent state.

What is needed is a method for making a scissoring-type CPP-MR sensorwith side shields to improve the stability of the magnetizationdirections of the two free layers.

SUMMARY OF THE INVENTION

Embodiments of this invention relate to methods for making a scissoringtype CPP-MR sensor with exchange-coupled soft side shields. The softside shields prevent reading of recorded bits in tracks adjacent thetrack being read and also bias the magnetization directions of the twofree layers (FL1 and FL2) longitudinally so they have a preferreddirection antiparallel to one another in the quiescent state. First, allof the layers making up the sensor stack are deposited as full films onthe bottom along-the-track shield (S1). A layer of photoresist is thenlithographically patterned to define two side edges of the sensor, andthe sensor stack is ion milled to remove the layers outside the sensorside edges down to S1. This results in a sloping tail at the base of themilled stack. The side regions are then refilled by deposition of aninsulating layer, typically alumina or a silicon nitride (SiNx), on S1and on the side edges. Next, the lower soft magnetic layers of theexchange-coupled side shields for biasing FL1 are deposited by ion beamdeposition, which also coats the insulating layer up to and past theside edges of FL2. The material of the lower soft magnetic layersadjacent the side edges of FL2 is then removed by oblique angle ion beammilling, preferably at an angle between 50 and 85 degrees from a normalto S1. This cleans the insulating layer of the soft magnetic material onthe vertical edges of the sensor without significant damage to orremoval of the main body of the lower soft magnetic layers. Next, thematerial for the antiparallel-coupling (APC) layers for theexchange-coupled side shields is deposited, followed by deposition ofthe material for the upper soft magnetic layers of the exchange-coupledside shields for biasing FL2. The upper layers of the exchange-coupledside shields may then be exchange-coupled to the upper along-the-trackmagnetic shield S2.

For a fuller understanding of the nature and advantages of the presentinvention, reference should be made to the following detaileddescription taken together with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top view of a conventional magnetic recording harddisk drive with the cover removed.

FIG. 2 is an enlarged end view of the slider and a section of the disktaken in the direction 2-2 in FIG. 1.

FIG. 3 is a view in the direction 3-3 of FIG. 2 and shows the ends ofthe read/write head as viewed from the disk.

FIG. 4A is a cross-sectional schematic view facing the air-bearingsurface (ABS) of the scissoring-mode CPP-MR read head according to theprior art and showing the stack of layers located between the magneticshield layers.

FIG. 4B is a view of section 4B-4B of FIG. 4A and shows the ABS in edgeview and the hard biasing layer recessed from the ABS.

FIG. 4C is a top view of the plane of section 4C-4C of FIG. 4B and showsthe ABS in edge view and the hard biasing layer recessed from the ABS.

FIG. 5A is a sectional view facing the ABS of a CPP-MR sensor withexchange-coupled soft side shields.

FIG. 5B is a top view of the plane of section 5B-5B of FIG. 5A.

FIGS. 6A-6D are sectional views facing the ABS and illustrating steps inthe method for forming the exchange-coupled side shields in the CPP-MRread head shown in FIGS. 5A-5B.

FIG. 7 is a sectional view showing the exchange coupling of the uppersoft side shield layers with the top shield S2.

DETAILED DESCRIPTION OF THE INVENTION

The scissoring-type CPP magnetoresistive (MR) sensor of this inventionhas application for use in a magnetic recording disk drive, theoperation of which will be briefly described with reference to FIGS.1-3. FIG. 1 is a block diagram of a conventional magnetic recording harddisk drive. The disk drive includes a magnetic recording disk 12 and arotary voice coil motor (VCM) actuator 14 supported on a disk drivehousing or base 16. The disk 12 has a center of rotation 13 and isrotated in direction 15 by a spindle motor (not shown) mounted to base16. The actuator 14 pivots about axis 17 and includes a rigid actuatorarm 18. A generally flexible suspension 20 includes a flexure element 23and is attached to the end of arm 18. A head carrier or air-bearingslider 22 is attached to the flexure 23. A magnetic recording read/writehead 24 is formed on the trailing surface 25 of slider 22. The flexure23 and suspension 20 enable the slider to “pitch” and “roll” on anair-bearing generated by the rotating disk 12. Typically, there aremultiple disks stacked on a hub that is rotated by the spindle motor,with a separate slider and read/write head associated with each disksurface.

FIG. 2 is an enlarged end view of the slider 22 and a section of thedisk 12 taken in the direction 2-2 in FIG. 1. The slider 22 is attachedto flexure 23 and has an air-bearing surface (ABS) 27 facing the disk 12and a trailing surface 25 generally perpendicular to the ABS. The ABS 27causes the airflow from the rotating disk 12 to generate a bearing ofair that supports the slider 20 in very close proximity to or nearcontact with the surface of disk 12. The read/write head 24 is formed onthe trailing surface 25 and is connected to the disk drive read/writeelectronics by electrical connection to terminal pads 29 on the trailingsurface 25. As shown in the sectional view of FIG. 2, the disk 12 is apatterned-media disk with discrete data tracks 50 spaced-apart in thecross-track direction, one of which is shown as being aligned withread/write head 24. The discrete data tracks 50 have a track width TW inthe cross-track direction and may be formed of continuous magnetizablematerial in the circumferential direction, in which case thepatterned-media disk 12 is referred to as a discrete-track-media (DTM)disk. Alternatively, the data tracks 50 may contain discrete dataislands spaced-apart along the tracks, in which case the patterned-mediadisk 12 is referred to as a bit-patterned-media (BPM) disk. The disk 12may also be a conventional continuous-media (CM) disk wherein therecording layer is not patterned, but is a continuous layer of recordingmaterial. In a CM disk the concentric data tracks with track width TWare created when the write head writes on the continuous recordinglayer.

FIG. 3 is a view in the direction 3-3 of FIG. 2 and shows the ends ofread/write head 24 as viewed from the disk 12. The read/write head 24 isa series of thin films deposited and lithographically patterned on thetrailing surface 25 of slider 22. The write head includes aperpendicular magnetic write pole (WP) and may also include trailingand/or side shields (not shown). The scissoring-type CPP MR sensor orread head 100 is located between two magnetic shields S1 and S2. Theshields S1, S2 are formed of magnetically permeable material, typicallya NiFe alloy, and may also be electrically conductive so they canfunction as the electrical leads to the read head 100. The shieldsfunction to shield the read head 100 from recorded data bits that areneighboring the data bit being read. Separate electrical leads may alsobe used, in which case the read head 100 is formed in contact withlayers of electrically conducting lead material, such as ruthenium,tantalum, gold, or copper, that are in contact with the shields S1, S2.FIG. 3 is not to scale because of the difficulty in showing very smalldimensions. Typically each shield S1, S2 is several microns thick in thealong-the-track direction, as compared to the total thickness of theread head 100 in the along-the-track direction, which may be in therange of 20 to 40 nm.

FIG. 4A is an enlarged sectional view facing the ABS of a prior artscissoring-type CPP GMR or TMR read head comprising a stack of layers,including dual sensing or free layers, formed between the two magneticshield layers S1, S2. S1 and S2 are typically electroplated NiFe alloyfilms. The lower shield 51 is typically polished by chemical-mechanicalpolishing (CMP) to provide a smooth substrate for the growth of thesensor stack. This may leave an oxide coating which can be removed witha mild etch just prior to sensor deposition. The sensor layers are afirst ferromagnetic free or sensing layer (FL1) 150 having a magneticmoment or magnetization direction 151 and a second ferromagnetic free orsensing layer (FL2) 170 having a magnetic moment or magnetizationdirection 171.

FL1 and FL2 are typically formed of conventional ferromagnetic materialslike crystalline CoFe or NiFe alloys, or a multilayer of thesematerials, such as a CoFe/NiFe bilayer. Instead of these conventionalferromagnetic materials, FL1 and FL2 may be formed of or comprise aferromagnetic Heusler alloy, some of which are known to exhibit highspin-polarization in their bulk form. Examples of Heusler alloys includebut are not limited to the full Heusler alloys Co₂MnX (where X is one ormore of Al, Sb, Si, Sn, Ga, or Ge). Examples also include but are notlimited to the half Heusler alloys NiMnSb, PtMnSb, andCo₂FexCr_((1-x))Al (where x is between 0 and 1).

FL1 and FL2 comprise self-referenced free layers, and hence no pinned orpinning layers are required, unlike in conventional CPP spin-valve typesensors. FL1 and FL2 have their magnetization directions 151, 171,respectively, oriented in-plane and preferably generally orthogonal toone another in the absence of an applied magnetic field. While themagnetic moments 151, 171 in the quiescent state (the absence of anapplied magnetic field) are preferably oriented generally orthogonal,i.e., between about 70 and 90 degrees to each other, they may beoriented by less than generally orthogonal, depending on the bias pointat which the sensor 100 is operated. FL1 and FL2 are separated by anonmagnetic spacer layer 160. Spacer layer 160 is a nonmagneticelectrically conductive metal or metal alloy, like Cu, Au, Ag, Ru, Rh,Cr and their alloys, if the sensor 100 is a CPP GMR sensor, and anonmagnetic insulating material, like TiO₂, MgO or Al₂O₃, if the sensor100 is a CPP TMR sensor.

Located between the lower shield layer S1 and the FL1 are the bottomelectrical lead 130 and an underlayer or seed layer 140. The seed layer140 may be a single layer or multiple layers of different materials.Located between FL2 and the upper shield layer S2 are a capping layer180 and the top electrical lead 132. The leads 130, 132 are typically Taor Rh, with lead 130 serving as the substrate for the sensor stack.However, a lower resistance material may also be used. They are optionaland used to adjust the shield-to-shield spacing. If the leads 130 and132 are not present, the bottom and top shields S1 and S2 are used asleads, with S1 then serving as the substrate for the deposition of thesensor stack. The underlayer or seed layer 140 is typically one or morelayers of NiFeCr, NiFe, Ta, Cu or Ru. The capping layer 180 providescorrosion protection and is typically formed of single layers, like Ruor Ta, or multiple layers of different materials, such as a Cu/Ru/Tatrilayer.

In the presence of an external magnetic field in the range of interest,i.e., magnetic fields from recorded data on the disk 12, themagnetization directions 151 and 171 of FL1 and FL2, respectively, willrotate in opposite directions. Thus when a sense current I_(s) isapplied from top lead 132 perpendicularly through the stack to bottomlead 130, the magnetic fields from the recorded data on the disk willcause rotation of the magnetizations 151, 171 in opposite directionsrelative to one another, which is detectable as a change in electricalresistance.

FIG. 4B is a sectional view along the plane 4B-4B in FIG. 4A and showsthe ABS as a plane normal to the paper. FIG. 4C is a view along theplane 4C-4C in FIG. 4B with the ABS as a plane normal to the paper andshows the trackwidth (TW) and stripe height (SH) dimensions of thesensor. FIG. 4C shows the in-plane generally orthogonal relativeorientation of magnetization directions 151, 171, with magnetizationdirection 151 being depicted as a dashed arrow because it is themagnetization direction of underlying FL1 which is not visible in FIG.4C. As can be seen from FIG. 4C, in the absence of an applied magneticfield, the magnetization directions or vectors 151, 171 have parallelcomponents in the sensing direction of the magnetic field to be detected(perpendicular to the ABS) and antiparallel components in the orthogonaldirection (parallel to the ABS). FIGS. 4B and 4C show a hard bias layer190 recessed from the ABS. The hard bias layer 190 is magnetizedin-plane in the direction 191. Hard bias layer 190 stabilizes or biasesthe FL1, FL2 magnetization directions 151, 171 so they make a non-zeroangle relative to one another, preferably a generally orthogonalrelative orientation, by rotating them away from what would otherwise bean antiparallel orientation. Referring to FIG. 4C, the detected signalfield is generally perpendicular to the ABS and is aligned generallycollinearly with the bias field 191 from the hard bias layer 190.

While the hard bias field 191 at the sensor back edge will tend to alignthe magnetization directions 151, 171 of the two free layers FL1, FL2generally orthogonal relative to one another, there is no preference forthe specific directions of the magnetizations 151, 171. For example,referring to FIG. 4C, while FL1 magnetization direction 151 is depictedas pointing approximately −45 degrees (counter clockwise) relative tothe ABS, with FL2 magnetization direction 171 pointing approximately +45degrees (clockwise) relative to the ABS, it is just as likely that thesetwo magnetization directions could be switched (i.e., magnetizationdirection 151 could be at +45 degrees clockwise with magnetizationdirection 171 at −45 degrees counter clockwise).

Embodiments of this invention relate to methods for making a scissoringtype CPP MR sensor with exchange-coupled soft side shields, like thatdepicted in FIGS. 5A-5B. The soft side shields prevent reading ofrecorded bits in tracks adjacent the track being read and also bias theFL 1 and FL2 magnetization directions longitudinally so they have apreferred direction in the quiescent state. FIG. 5A is a sectional viewfacing the ABS of the sensor and FIG. 5B is a top view of the plane ofsection 5B-5B of FIG. 5A. FL1 and FL2 have respective magnetizationdirections 251, 271 and are separated by nonmagnetic spacer layer 260.FL1 is formed on seed layer 240 on shield 51 and capping layer 280 isformed on FL2 below shield S2. FL1, nonmagnetic spacer layer 260, andFL2 are separate from exchange-coupled soft-side shields 300, 350 at theside edges 275, 276 that essentially define the sensor TW. An insulatinglayer 285, such as alumina (Al₂O₃), at the side edges 275, 276electrically insulates FL1 and FL2 from the side shields 300, 350.

In the exchange-coupled side shield 300, which is identical to sideshield 350, soft magnetic layers 310, 320 are separated by a nonmagneticantiparallel-coupling (APC) layer 315, typically a 0.5-1 nm thick layerof Ru or Cr. To improve coupling, 1-2 nm thick layers of Co, Fe, or aCoFe alloy (not shown) may be located between the APC layer 315 and softmagnetic layers 310, 320, respectively. The thickness of the APC layer315 is chosen to provide adequate antiferromagnetic exchange coupling,resulting in the magnetization directions 311, 321 of soft magneticlayers 310, 320 being oriented antiparallel.

Thus layers 310, 320 (and also layers 360, 370 in exchange-coupled softside shield 350) are preferably an alloy comprising Ni and Fe withpermeability (μ) preferably greater than 10. Any of the known materialssuitable for use in the along-the-track shields S1 and S2 may be usedfor layers 310, 320. Specific compositions include NiFe_(x), where x isbetween 1 and 25, and (NiFe_(x))Mo_(y) or (NiFe_(x))Cr_(y), where y isbetween 1 and 8, where the subscripts are in atomic percent.

As shown in FIGS. 5A-5B, layers 320, 370 are aligned generallyvertically on the substrate (S1) with the side edges of FL2, and layers310, 360 are aligned generally vertically on the substrate with the sideedges of FL1. Thus the magnetization directions 321 of layer 320 and 371of layer 370 provide a longitudinal magnetic bias field to themagnetization 271 of FL2. Similarly, the magnetization directions 311 oflayer 310 and 361 of layer 360 provide a longitudinal magnetic biasfield to the magnetization 251 of FL1. This longitudinal biasing of Fl1and FL2 is in addition to the orthogonal biasing provided by hard biaslayer 290 with magnetization direction 291. The longitudinal biasingprovided by the exchange coupled soft side shields 300, 350 thus assuresthat the magnetization 271 of FL2 points to the left in FIG. 5B and thatthe magnetization 251 of FL1 points to the right in FIG. 5B. In additionto providing longitudinal biasing for FL1 and Fl2, the exchange-coupledsoft side shields 300, 350 also shield the sensor free layers FL1, FL2from recorded bits in adjacent tracks, i.e., tracks on either side ofthe TW region of the sensor.

The method for forming the exchange-coupled side shields in the CPP-MRread head shown in FIGS. 5A-5B will now be described using FIGS. 6A-6D.First, all of the layers making up the sensor stack, i.e., layers fromseed layer 240 up through capping layer 280, are deposited as full filmson S1, typically by sputter deposition. A thin silicon (Si) film is thendeposited as a full film on capping layer 280. The Si is an adhesionfilm for a subsequently deposited full film of hard mask material, likediamond-like carbon (DLC). A layer of photoresist is then deposited onthe DLC. The photoresist is then lithographically patterned to definethe two side edges 275, 276 of the sensor.

Next, as shown in FIG. 6A, an ion milling step removes the layersoutside the sensor side edges 275, 276 down to S1. However, present ionmilling techniques create a sloping tail at the base of the milledstack, as shown in FIG. 6A. The side regions are then refilled bydeposition of the insulating layer 285, typically alumina or a siliconnitride (SiN_(x)), on S1 and on the side edges 275, 276.

Next, as shown in FIG. 6B, the material for the lower soft magneticlayers 310, 360, are deposited to the desired thickness by ion beamdeposition. However, the IBD also coats the insulating layer 285 up toand past the side edges 275, 276 of the nonmagnetic spacer layer 260 andFL2. If this material were to remain adjacent the side edges of FL2 whenthe material of APC layers 315, 365 and the material for upper softmagnetic layers 320, 370 layers was deposited, the antiparallelexchange-coupled soft side shields would not function properly. This isbecause the magnetization direction of this soft magnetic materialadjacent to the sidewalls would be ill-defined, creating uncertainty inthe biasing of FL2. It is preferable to deposit layer 310 and layer 360by IBD rather than by sputtering since the directional nature of IBDminimizes the amount of material deposited along the edges 275, 276 ofFL2. Nevertheless, due to beam dispersion in IBD tooling, it isinevitable that some material from layers 310 and 360 will coat theedges 275, 276 of the sensor stack along FL2. Thus a critical step inone of the embodiments of the method of this invention is the removal ofthe material of the lower soft magnetic layers from adjacent the sideedge of FL2. This is achieved by oblique angle ion beam milling as shownin FIG. 6C. Oblique angle milling refers to the small angle relative tothe plane of the substrate (S1). This cleans the insulating layer 285 ofthe soft magnetic material without significant damage to or removal ofthe main body of the lower soft magnetic layers 310, 360 because thesputter removal rate of these soft magnetic materials is highlyangle-dependent. Therefore the ion milling is at an oblique angle,preferably between about 50 to 85 degrees relative to a normal to thesubstrate (S1), and is performed at a low voltage, e.g., between about100 to 300 V). After the oblique angle ion milling the lower softmagnetic layers 310, 360 have a thickness so that they are generallyaligned vertically with FL1. This cleaning of the sensor sidewalls canbe accomplished without substantial removal of the insulating layer 285because alumina (or other insulating oxides) are milled much more slowlythan the soft magnetic material (e.g., NiFe).

Next, as shown in FIG. 6D, the material for APC layers 315, 365(typically Ru or Cr) is ion beam deposited to a thickness between about0.5-1.0 nm, followed by IBD of the material for upper soft magneticlayers 320, 370. The material for upper soft magnetic layers 320, 370 isdeposited to a thickness so that layers 320, 370 will be generallyaligned vertically with FL2. In some implementations, the soft magneticmaterial in layers 320 and 370 will be directly exchange-coupled to theupper magnetic shield S2, in which case the boundary between layers 320and 370 and the upper shield S2 is ill-defined but not important.

As an alternative embodiment of the method, instead of IBD of thematerial for the lower soft magnetic layers 310, 360, this material canbe deposited by electroplating. After deposition of the insulating layer285, a thin seed layer, such as a 1 to 4 nm thick film of NiFe, can bedeposited by sputter deposition or IBD, followed by cleaning of the seedlayer material from the side edges using oblique angle ion milling. Thematerial for the lower soft magnetic layers 310, 360 is thenelectroplated on the seed layer to the desired thickness. This is thenfollowed by sputter deposition of the material for APC layers 315, 365and sputter deposition or IBD of the material for the upper softmagnetic layers 320, 370.

After formation of the exchange-coupled soft side shields 300, 350, asecond Si adhesion layer and second DLC layer are then deposited in theside regions over the two exchange-coupled soft side shields 300, 350.Due to the topographic selectivity of the process, the materialdeposited on top of the DLC above the capping layer is then removed bychemical-mechanical-polishing (CMP) assisted lift-off down to the DLClayers. The second DLC layer protects the soft bias layers 320, 370. Areactive ion etching (RIE) step then removes the DLC above the cappinglayer and the second DLC above the soft bias 320, 370. An ion millingstep is then performed to remove the Si layers. This is followed bydeposition of the top shield S2. Depending on method to stabilize thesoft-bias magnetization directions 321, 371, the layers 320, 370 can bedecoupled from S2 by a thin (less than 5 nm) non-magnetic spacer layerdeposited on top of the soft side shields 320, 370. Alternatively, thelayers 320, 370 can be directly coupled to S2 as described furtherbelow.

There are several ways to set the magnetization directions 321, 371 ofthe exchange-coupled soft side shields. One method is described withFIG. 7. First a base layer 380 of soft magnetic shield material (e.g.,NiFe) approximately 30 nm thick is deposited on the soft side shieldlayers 320, 370 and on top the capping layer 280. The base layer 380will serve as the base of the top shield S2 and will set themagnetization directions 321, 371 of the soft side shield layers 320,370. Then a thin (typically between about 0.5 to 1 nm)antiferromagnetic-coupling (AFC) layer 382 (e.g., Ru) is deposited onbase layer 380. AFC layer 382 will provide antiferromagnetic exchangecoupling between the base layer 380 and a subsequently deposited layer384 of soft magnetic upper shield material (e.g., NiFe) approximately 25nm thick. Finally, an antiferromagnetic (AF) layer 386 (e.g., IrMn) isdeposited on top of the upper shield layer 384. A magnetic field annealis then performed to set the magnetization direction 387 of the AF layer386 and the exchange pinning between the antiferromagnetic layer 386 andthe upper shield layer 384. The upper shield layer 384 will thus have amagnetization direction 385, which will cause the magnetizationdirections 321, 371 of the soft side shield layers 320, 371 to beantiparallel to magnetization direction 385 due to antiferromagneticexchange coupling across AFC layer 382.

While the present invention has been particularly shown and describedwith reference to the preferred embodiments, it will be understood bythose skilled in the art that various changes in form and detail may bemade without departing from the spirit and scope of the invention.Accordingly, the disclosed invention is to be considered merely asillustrative and limited in scope only as specified in the appendedclaims.

What is claimed:
 1. A method for making a scissoring typecurrent-perpendicular-to-the-plane magnetoresistive sensor, the sensorhaving a first free ferromagnetic layer (FL1) and a second freeferromagnetic layer (FL2) separated by a nonmagnetic spacer layer,wherein the FL1 and FL2 magnetization directions are free to rotaterelative to one another in the presence of an external magnetic field tobe sensed, the method comprising: providing a substrate; depositing FL1,the nonmagnetic spacer layer and FL2 on the substrate; patterning FL1,the nonmagnetic spacer layer and FL2 to define spaced-apart side edgesat FL1, the nonmagnetic spacer layer and FL2; depositing a layer ofinsulating material on the substrate and on the side edges; depositing afirst layer of soft ferromagnetic material on the substrate and incontact with the insulating layer at the side edges of FL1, thenonmagnetic spacer layer and FL2; performing oblique angle ion millingof the first layer of soft ferromagnetic material to remove the firstlayer of soft ferromagnetic material adjacent the side edges of FL2;depositing an antiparallel coupling (APC) layer on the first layer ofsoft ferromagnetic material; and depositing a second layer of softferromagnetic material on the APC layer and in contact with theinsulating layer at the side edges of FL2.
 2. The method of claim 1wherein depositing the first layer of soft ferromagnetic materialcomprises depositing the first layer of soft ferromagnetic material byion beam deposition.
 3. The method of claim 1 wherein depositing thefirst layer of soft ferromagnetic material comprises depositing thefirst layer of soft ferromagnetic material by electroplating.
 4. Themethod of claim 1 wherein performing oblique angle ion milling comprisesperforming said milling at an angle greater than or equal to 50 degreesand less than or equal to 85 degrees from a normal to the substrate. 5.The method of claim 1 wherein performing oblique angle ion millingcomprises performing said milling at a voltage greater than or equal to100 V degrees and less than or equal to 300 V.
 6. The method of claim 1wherein depositing a layer of insulating material on the substrate andon the side edges comprises depositing a layer of alumina.
 7. The methodof claim 1 wherein depositing a first layer of soft ferromagneticmaterial on the substrate and in contact with the insulating layer atthe side edges of FL1, the nonmagnetic spacer layer and FL2 comprisesdepositing material selected from NiFe_(x) where x is between 1 and 25,(NiFe_(x))Mo_(y) where y is between 1 and 8, and (NiFe_(x))Cr_(y) wherey is between 1 and 8, where the subscripts are in atomic percent.
 8. Themethod of claim 1 further comprising: depositing a base layer of softferromagnetic material on the second layer of ferromagnetic material;depositing an antiferromagnetic coupling (AFC) layer on the base layer;depositing an upper layer of soft ferromagnetic material on the AFClayer; depositing an antiferromagnetic layer (AF) on the AFC layer; andannealing the AF layer in the presence of a magnetic field.
 9. A methodfor making a scissoring type current-perpendicular-to-the-planemagnetoresistive sensor, the sensor having a first free ferromagneticlayer (FL1) and a second free ferromagnetic layer (FL2) separated by anonmagnetic spacer layer, wherein the FL1 and FL2 magnetizationdirections are free to rotate relative to one another in the presence ofan external magnetic field to be sensed, the method comprising:providing a bottom shield S1; depositing FL1, the nonmagnetic spacerlayer and FL2 on S1; patterning FL1, the nonmagnetic spacer layer andFL2 to define spaced-apart side edges at FL1, the nonmagnetic spacerlayer and FL2; depositing a layer of insulating material on S1 and onthe side edges; depositing, by ion beam deposition, a first layer ofsoft ferromagnetic material on S1 and in contact with the insulatinglayer at the side edges of FL1, the nonmagnetic spacer layer and FL2;performing oblique angle ion milling of the first layer of softferromagnetic material to remove the first layer of soft ferromagneticmaterial adjacent the side edges of FL2, said ion milling beingperformed at an greater than or equal to 50 degrees and less than orequal to 85 degrees from a normal to S1; depositing an antiparallelcoupling (APC) layer on the first layer of soft ferromagnetic material;and depositing a second layer of soft ferromagnetic material on the APClayer and in contact with the insulating layer at the side edges of FL2.10. The method of claim 9 wherein performing oblique angle ion millingcomprises performing said milling at a voltage greater than or equal to100 V degrees and less than or equal to 300 V.
 11. The method of claim 9wherein depositing a layer of insulating material on S1 and on the sideedges comprises depositing a layer of alumina.
 12. The method of claim 9wherein depositing a first layer of soft ferromagnetic material on S1and in contact with the insulating layer at the side edges of FL1, thenonmagnetic spacer layer and FL2 comprises depositing material selectedfrom NiFe_(x) where x is between 1 and 25, (NiFe_(x))Mo_(y) where y isbetween 1 and 8, and (NiFe_(x))Cr_(y) where y is between 1 and 8, wherethe subscripts are in atomic percent.